Photochromic polyurethanes

ABSTRACT

The present invention relates to a novel photochromic polyurethane consisting essentially of an isocyanate reactive mixture consisting essentially of: i) from about 40 to about 85% by weight of one or more polyols having a nominal functionality of from 2 to 4 and molecular weights of from 500 to 6000 g/mole; ii) from about 15 to about 60% by weight of one or more diols or triols or mixtures thereof having a functionality of from 2 to 3 and molecular weights of from 62 to 499; b) an aliphatic polyisocyanate having a functionality ranging from about 2 to about 3; and c) a photochromic compound selected from a group consisting of spirooxazines, fulgides, fulgimides, and naphthopyrans, wherein the photochromic compound is present in an amount of 0.01 to 5 parts per hundred parts by weight of the isocyanate reactive mixture.

This application is a Continuation-In-Part of application Ser. No.08/999,217, filed Dec. 29, 1997 NOW ABANDONED.

FIELD OF THE INVENTION

The present invention relates to polyurethanes with improvedphotochromic behavior.

BACKGROUND OF THE INVENTION

Articles which have organic photochromic material(s) applied to orincorporated therein are characterized in that upon exposure toelectromagnetic radiation or to solar light they exhibit a reversiblechange in color and in light transmission. Once the exposure to theoriginal radiation has been discontinued, the composition returns to itsoriginal color, or colorless state. Recently, photochromic plasticmaterials, most notably, such compositions which may be suitable for thepreparation of ophthalmic lenses, films and automotive head lamp lenseshave been the focus of attention in the relevant arts. Plastic materialsas the medium for the preparation of such lenses allow for thepreparation of lighter and thinner lenses than do the traditionally usedglass. Also of interest are the applications of photochromic technologyto automotive, aircraft transparencies and greenhouse architecture andother glazing applications. It is known that photochromic behavior maybe imparted to glass and to certain plastic materials by using inorganicand organic dyes respectively. Photochromic articles prepared fromsynthetic organic resins such as homopolymers of a poly(allyl carbonate)monomer are known (U.S. Pat. Nos. 4,994,208, 5,246,630, 5,221,721 and5,200,483.)

U.S. Pat. No. 5,244,602 describes a naphthopyran useful for photochromicpolymers and also organic hosts such as polyurethanes for suchmaterials. However, a detailed description of the polyurethane is notgiven.

In McBain, et al. (U.S. Pat. No. 4,994,208), it was demonstrated thatphotochromic performance of matrices prepared by the free radicalpolymerization of polyol (allyl carbonates), e.g., diethylene glycolbis(allyl carbonate), could be improved by the incorporation of 10 to 40weight percent of an aliphatic polyurethane having terminal ethylenicunsaturation. The polyurethanes described in this reference can berepresented by the following expression:

    D-R-B-A-B-R-D

Here, D represents the terminal functional group containing ethylenicunsaturation, R represents a bivalent alkylene group containing from 1to 10 carbon atoms, B represents an aliphatic bis carbamate moietyoriginating from the corresponding aliphatic diisocyanate, and Arepresents the residue of a saturated aliphatic polyol (e.g., a C₂ -C₆alkane diol, a polyether, polyester, or polycarbonate diol). In thesesystems, the polyurethane having terminal ethylenic unsaturationundergoes free radical polymerization with the polyol (allyl carbonate)to form a urethane containing copolymer.

In Selvig (U.S. Pat. No. 5,200,483), it was shown that the compositionsdescribed in McBain, et al. could be improved upon (in terms of castingpot life and yellowness) by using appropriate mixtures of allyl andacrylyl groups for the terminal unsaturation in the polyurethanes.

The technology described by Selvig and McBain, et al. requires either aphotochromic dye which is resistant to the effects of the peroxy typeinitiator (see Selvig, Col. 11, lines 53-56) or a secondary processingstep, in which the dye is "imbibed" into the finished polymer matrix.(see Selvig, Examples 7 and 10).

Surprisingly, we have now found that polyurethane matrices of theinventive composition are optically clear and have excellentphotochromic performance. Since the systems described in our inventiondo not cure by a free radical mechanism, commercially availablephotochromic dyes can be added during the casting stage, withoutinterfering in the cure of the polymer or without detriment to the dye'sultimate performance.

SUMMARY OF THE INVENTION

The present invention relates to a novel photochromic polyurethanecomprising an isocyanate reactive mixture comprising: i) from about 40to about 85% by weight of one or more polyols having a nominalfunctionality of from 2 to 4 and molecular weights of from 500 to 6000g/mole; ii) from about 15 to about 60% by weight of one or more diols ortriols or mixtures thereof having a functionality of from 2 to 3 andmolecular weights of from 62 to 499; b) an aliphatic polyisocyanatehaving a functionality ranging from about 2 to about 3; and c) aphotochromic compound selected from a group consisting of spirooxazines,fulgides, fulgimides, and naphthopyrans, wherein the photochromiccompound is present in an amount of 0.01 to 5 parts per hundred parts byweight of the isocyanate reactive mixture.

An object of the present invention is to produce a transparentpolyurethane material in which the photochromic dyes fade back to the"uncolored state" rapidly, that is, the absorbance of this novelpolyurethane returns to less than 50% of the "colored state" within twominutes after the light source is removed. This is accomplished byadding an appropriate amount of a high molecular weight polyol componentinto a polyurethane.

DETAILED DESCRIPTION OF THE INVENTION

The photochromic polyurethane of the present invention comprises anisocyanate reactive mixture comprising from about 40 to about 85% byweight, preferably 50 to 70% by weight, of one or more polyols having anominal functionality of from 2 to 4 and molecular weights of from 500to 6000 g/mole; ii) from about 15 to about 60% by weight, preferably 30to 50% by weight, of one or more diols or triols or mixtures thereofhaving a functionality of from 2 to 3 and molecular weights of from 62to 499 and b) an aliphatic polyisocyanate having a functionality of lessthan about 3, preferably 2.

The polyols of the present invention are those conventionally employedin the art for the preparation of polyurethane cast elastomers.Preferably, the polyols have molecular weights (number average) withinthe range of 500 to 6,000, preferably 1000 to 3,000. The functionalityof the polyol ranges from about 2 to 4, preferably about 2.0. From about40 to 85 percent by weight of these polyols are present in theisocyanate reactive mixture. Naturally, and often times advantageously,mixtures of such polyols are also possible. Examples of the suitablepolyols include polyether polyols, polyester polyols, and polycarbonatepolyols.

Suitable polyether polyols are known, for example, from GermanOffenlegungsschrift 2,905,975, for example, such as polypropyleneglycol. Other suitable polyethers are also derived from propylene oxideand/or ethylene oxide with molecular weights of about 500 to 6000 (OHnumbers of 225 to 19) based on difunctional starters such as water,ethylene glycol or propylene glycol are also preferred. These preferredcompounds include copolymers of ethylene oxide and propylene oxide withabout 0 to 20% by weight of the oxides being ethylene oxides.Poly(tetramethylene glycol) diols having molecular weights of about 500to 5000 (OH numbers of 18.7 to 224) are also preferred.

The suitable polyester polyols include the ones which are prepared bypolymerizing ε-caprolactone using an initiator such as ethylene glycol,ethanolamine and the like. Further suitable examples are those preparedby esterification of polycarboxylic acids. Further suitable polyesterpolyols include reaction products of polyhydric, preferably dihydricalcohols to which trihydric alcohols may be added and polybasic,preferably dibasic carboxylic acids. Instead of these polycarboxylicacids, the corresponding carboxylic acid anhydrides or polycarboxylicacid esters of lower alcohols or mixtures thereof may be used forpreparing the polyesters. The polycarboxylic acids may be aliphatic,cycloaliphatic, aromatic and/or heterocyclic and they may besubstituted, e.g., by halogen atoms, and/or unsaturated. The followingare mentioned as examples: succinic acid; adipic acid; suberic acid;azelaic acid; sebacic acid; phthalic acid; isophthalic acid; trimelliticacid; phthalic acid anhydride; tetrahydrophthalic acid anhydride;hexahydrophthalic acid anhydride; tetrachlorophthalic acid anhydride,endomethylene tetrahydrophthalic acid anhydride; glutaric acidanhydride; maleic acid; maleic acid anhydride; fumaric acid; dimeric andtrimeric fatty acids such as oleic acid, which may be mixed withmonomeric fatty acids; dimethyl terephthalates and bis-glycolterephthalate. Suitable polyhydric alcohols include, e.g., ethyleneglycol; propylene glycol-(1,2) and -(1,3); butylene glycol-(1,4) and-(1,3); hexanediol-(1,6); octanediol-(1,8); neopentyl glycol;(1,4-bis-hydroxymethylcyclohexane); 2-methyl-1,3-propanediol;2,2,4-trimethyl-1,3-pentanediol; triethylene glycol; tetraethyleneglycol; polyethylene glycol; dipropylene glycol; polypropylene glycol;dibutylene glycol and polybutylene glycol, glycerine andtrimethlyolpropane. A preferred polyester polyol is butylene adipate.

Suitable diols and triols with molecular weights of 62 to 499 used inthe present invention include the polyhydric alcohols listed to formpolyester polyols. Triols such as trimethylolpropane (TMP), glycerine orlow MW polypropylene oxide polyols prepared from these or similartrifunctional starters are preferred.

A suitable polycarbonate polyol includes polyhexamethylene carbonate.Polycarbonates based on diols listed above are prepared by the reactionof the diol and a dialkyl carbonate as described in U.S. Pat. No.4,160,853.

Suitable additives for use in the present invention include the tinatalysts.

In accordance with the present invention, the aliphatic olyisocyanatecomponent, having a viscosity of less than about 20,000 mPa.s at 25° C.and having an average NCO functionality of 2 to 3, most preferably about2, is generally in the form of an NCO prepolymer or a polyisocyanateadduct, more preferably a polyurethane prepolymer. Suitablepolyisocyanate adducts for the present invention may be based, forexample, on organic aliphatic diisocyanates including, for example,1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate,2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 1,12-dodecamethylenediisocyanate, cyclohexane-1,3- and -1,4-diisocyanate,1-isocyanato-2-isocyanatomethyl cyclopentane,1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane (isophoronediisocyanate or IPDI), bis-(4-isocyanatocyclohexyl)-methane,2,4'-dicyclohexylmethane diisocyanate, 1,3- and1,4-bis-(isocyanatomethyl)-cyclohexane,bis-(4-isocyanato-3-methylcyclohexyl)-methane,α,α,α',α'-tetramethyl-1,3- and/or -1,4-xylylene diisocyanate,1-isocyanato-1-methyl-4(3)-isocyanatomethyl cyclohexane, 2,4- and/or2,6-hexahydrotoluylene diisocyanate, and mixtures thereof. It ispreferred that the isocyanate be based on mixtures of the variousstereoisomers of bis-(4-isocyanatocyclohexl)-methane.

The dyes suitable in the context of the invention are photochromiccompounds selected from the group consisting of benzopyrans,naphthopyrans, spirobenzopyrans, spironaphthopyrans, spirobenzoxazines,spironaphthoxazines, fulgides and fulgimides. Such photochromiccompounds have been reported in the literature including U.S. Pat. Nos.4,826,977; 4,931,221; 5,106,998; 5,552,090; 5,628,935 and 5,565,147 (allincorporated herein by reference).

The color range of the naphthopyrans suitable in the present inventionis 410 to 500 nm, thus they impart a yellow or orange coloration intheir darkened state. In the faded, or bleached condition, the materialsexhibit a colorless or pale yellow coloration. The present invention maybe used in a mixture or combined with suitable organic photochromiccompounds, to obtain, after activation, the formation of neutralcoloring such as green, brown and grey. Particularly useful for thepurpose are photochromic compounds belonging to the group ofnaphthopyrans, spiro-indolino-oxazines and spiro-indolino pyrans whichare known and are available in commerce. These have a high quantumefficiency for coloring, a good sensitivity and saturated opticaldensity, and an acceptable bleach or fade rate. These compounds may berepresented by the following graphic formulae IA1, IA2, and IA3 in whichthe letters a through n represent the sides of the naphthopyran rings,and the numbers represent the numbering of the ring atoms of thenaphthopyrans: ##STR1## In graphic formulae IA1, IA2, and IA3, the grouprepresented by A is a substituted or un-substituted, five or six memberheterocyclic ring fused to the g, i, or l side of the naphthopyran andis represented by the following graphic formulae IIA through IIF:##STR2##

In graphic formulae IIA through IID, X may be an oxygen or a nitrogenatom, the nitrogen atom being substituted with hydrogen or a C₁ -C₄alkyl. R₁ may be hydrogen, C₁ -C₆ alkyl, substituted or unsubstitutedphenyl, carboxy, or C₁ -C₆ alkoxycarbonyl. Preferably, R₁ is hydrogen,C₁ -C₃ alkyl, substituted or unsubstituted phenyl, carboxy, or C₁ -C₃alkoxycarbonyl. R₂ may be hydrogen, C₁ -C₆ alkyl, or substituted orunsubstituted phenyl. Preferably, R₂ is hydrogen, C₁ -C₃ alkyl, orsubstituted or unsubstituted phenyl. R₃ and R₄ may each be hydrogen, C₁-C₆ alkyl or phenyl. Preferably, R₃ and R₄ are each hydrogen, C₁ -C₃alkyl, or phenyl, R₅ and R₆ may each be hydrogen, C₁ -C₆ alkyl, phenyl,hydroxy, C₁ -C₆ alkoxy, or acetoxy. Preferably, R₅ and R₆ are eachhydrogen, C₁ -C₃ alkyl, phenyl, hydroxy, C₁ -C₃ alkoxy, or acetoxy, R₇,R₈, and R₁₀ may each be hydrogen, C₁ -C₆ alkyl, or phenyl, provided thatwhen R₇ is phenyl, R₈ is hydrogen or C₁ -C₆ alkyl and when R₈ is phenylR₇ is hydrogen or C₁ -C₆ alkyl. Preferably, R₇, R₈, and R₁₀ are eachhydrogen, C₁ -C₃ alkyl, or phenyl. Most preferably, R₁, R₂ R₃, R₄, R₅,R₆, R₇, R₈, and R₁₀ are each hydrogen or methyl. R₁₁, R₁₂, R₁₃, R₁₄,R₁₅, and R₁₆ may each be hydrogen, C₁ -C₆ alkyl, C₁ -C₆ alkoxy, orphenyl, Preferably, R₁₁, R₁₂, R₁₃, R₁₄, R₁₅, and R₁₆ are each hydrogen,C₁ -C₃ alkyl, C₁ -C₃ alkoxy, or phenyl. Most preferably, R₁₁, R₁₂, R₁₃,R₁₄, R₁₅, and R₁₆ are each hydrogen, methyl, or methoxy.

In graphic formulae IIE and IIF, R₁₇ may be hydrogen, C₁ -C₆ alkyl,substituted or unsubstituted phenyl, or halogen. Preferably, R₁₇ ishydrogen, C₁ -C₃ alkyl, substituted or unsubstituted phenyl, or halogen.Most preferably, R₁₇ is hydrogen, methyl, or chloro. R₁₈ may behydrogen, C₁ -C₆ alkyl, phenyl, carboxy, C₁ -C₆ alkoxy-carbonyl, or C₁-C₆ haloalkoxycarbonyl. Preferably, R₁₈ is hydrogen, C₁ -C₃ alkyl,phenyl, carboxy, C₁ -C₃ alkoxycarbonyl, or C₁ -C₃ haloalkoxycarbonyl.R₁₉ and R₂₀ may each be hydrogen, C₁ -C₆ alkyl, or phenyl. Preferably,R₁₉ and R₂₀ are each hydrogen, C₁ -C₃ alkyl, or phenyl. Most preferably,R₁₈, R₁₉, and R₂₀ are each hydrogen or methyl. R₁ -R₂₀ the phenylsubstituents may be C₁ -C₃ alkyl and the halogen or (halo) groups may bechloro or bromo.

In graphic formulae IA1, IA2, and IA3, B and B' may each be selectedfrom the group consisting of (i) the substituted or unsubstituted arylgroups phenyl and naphthyl; (ii) the substituted or unsubstitutedheterocyclic aromatic groups pyridyl, furyl, benzofuryl, thienyl, andbenzothienyl; and (iii) B and B' taken together form the adamantylgroup. The aryl and heterocyclic substituents of B and B' may each beselected from the group consisting of hydroxy, C₁ -C₃ alkyl, C₁ -C₅haloalkyl, which includes mono-, di-, and trihalo substituents, C₁ -C₅alkoxy, C₁ -C₅ alkoxy(C₁ -C₄)alkyl, C₁ -C₅ dialkylamino, acryloxy,methacryloxy, and halogen, said halogen or (halo) groups being fluoro,chloro, or bromo.

Preferably, B and B' are represented respectively by the followinggraphic formulae: ##STR3##

In graphic formulae IIIA and IIIB, Y₁ and Z₁ may each be selected fromthe group consisting of hydrogen, C₁ -C₅ alkyl, C₁ -C₅ alkoxy, fluoro,and chloro; Y₂ and Z₂ are each selected from the group consisting of C₁-C₅ alkyl, C₁ -C₅ alkoxy, hydroxy, halogen, e.g., chloro, fluoro, andbromo, acryloxy, and methacryloxy, and a and b are each integers from 0to 2. Most preferably, Y₁ and Z₁ are each hydrogen, C₁ -C₃ alkyl, C₁ -C₃alkoxy, or fluoro, Y₂ and Z₂ are each C₁ -C₃ alkyl or C₁ -C₃ alkoxy, ais the integer 0 or 1, and b is an integer from 0 to 2.

The preferred naphthopyrans of the present invention are represented inthe following graphic formula IB. In graphic formula IB, the A grouprepresents formulae IIA through IID with X being an oxygen atom,formulae IIE and IIF. The A group is fused so that the oxygen atom offormulae IIA through IIF is attached to the number 8 carbon atom of thenaphtho portion of the naphthopyran. ##STR4##

A still preferred dye may be described as naphthopyrans substituted atthe 3 position of the pyran ring with (i) an aryl substituent and (ii) aphenyl substituent having a 5- or 6-member oxygen and/or nitrogencontaining heterocyclic ring fused at the number 3 and 4 carbon atoms ofthe phenyl substituent and with a nitrogen-containing heterocyclic ringat the 6 position of the naphthyl portion of the naphthopyran compound.These compounds may be represented by the following graphic formula:##STR5##

In graphic formula I, R₁ may be C₁ -C₁₀ alkyl, halogen, or the group,--O--L, wherein L is a C₁ -C₁₂ alkyl, e.g., methyl, ethyl, propyl,butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl,said halogen being chloro, fluoro, or bromo, and a is the integer 0, 1or 2. Preferably, R₁ is C₁ -C₅ alkyl, fluoro, bromo or the group,--O--L, wherein L is C₁ -C₄ alkyl and a is the integer 0 or 1. Mostpreferably, R₁ is C₁ -C₃ alkyl, fluorine or the group --O--L, wherein Lis methyl, and a is the integer 0 or 1.

In graphic formula 1, R₂ may be a saturated, unsubstituted or monoordi-substituted nitrogen containing heterocyclic group selected from thefollowing groups represented by graphic formulae IA through IG: ##STR6##wherein E and F in graphic formula IC, are each a nitrogen or carbonatom, provided that when E is nitrogen, F is a carbon atom, and G ingraphic formula ID, is a nitrogen, oxygen, or carbon atom and H is anitrogen or carbon atom, provided that when H is nitrogen, G is a carbonatom. Examples of R₂ groups include aziridino, azetidino, 1-pyrrolidyl,I-pyrrolinyl, 1-imidazolidyl, 2-imidazolin-1-yl, 2-pyrazolidyl,3-pyrazolin-2-yl, morpholino, piperidino, piperazinyl,4-methyl-1-piperazinyl, 1,4,5,6,-tetra-hydropyrimidinyl, 1-indolinyl,hexamethyleneimino, and heptamethyleneimino. The substituents for R₂ canbe C₁ -C₆ alkyl and/or C₁ -C₆ alkoxy. Preferably, R₂ is an unsubstitutedor mono-substituted member of the group consisting of indolinyl,morpholino, and piperidino. More preferably, R₂ is morpholino.

B may be the substituted or unsubstituted aryl group, naphthyl orphenyl, said aryl substituents being C₁ -C₅ alkyl, halo(C₁ -C₅)alkyl,hydroxy, C₁ -C₅ alkoxy, C₁ -C₄ alkoxy(C₁ -C₄)alkyl, halogen, morpholino,piperidino, or R(R")N-, wherein R and R" are each hydrogen or C₁ -C₃alkyl, said halogen (or halo) groups being fluoro or chloro. Preferably,B is represented by the following graphic formula II: ##STR7##

In graphic formula 11, R₆ is hydrogen, C₁ -C₄ alkyl, C₁ -C₄ alkoxy,fluoro, or chloro and each R₇ is a C₁ -C₄ alkyl, C₁ -C₄ alkoxy, hydroxy,chloro, or fluoro and d is an integer from 0 to 2. Preferably, R₆ ishydrogen and R₇ is selected from the group consisting of fluoro, methyland methoxy.

B' may be represented by one of the following graphic formulae III orIV: ##STR8##

In graphic formula liI and IV, X is oxygen or nitrogen and Y is carbonor oxygen, provided that when X is nitrogen, Y is carbon; R₄ and R₅ areeach hydrogen or C₁ -C₅ alkyl; each R₃ is a C₁ -C₅ alkyl, C₁ -C₅ alkoxy,hydroxy, or halogen, said halogen substituent being chloro, fluoro, orbromo, and c is an integer from 0 to 3, e.g., 0, 1, 2, or 3. Preferably,B' is represented by graphic formula III or IV, wherein X is oxygen; Yis carbon or oxygen; R₄ and R₅ are each hydrogen or C₁ -C₄ alkyl; eachR₃ is a C₁ -C₄ alkyl, C₁ -C₄ alkoxy, hydroxy, or fluoro; and c is theinteger 0, 1 or 2. Most preferably, B' is 2,3-dihydroxybenzofuran-5-yi,2-methyldihydroxybenzofuran-5-yI, indoline-5-yl,1,2,3,4-tetrahydroquinoline-6-yl, chroman-6-yl or 1,3-benzodioxole-5-yl.

In graphic formula III, when R₄ and R₅ are H and when X is oxygen and Yis carbon and c is zero, the group is a 2,3-dihydrobenzo-furan-5-yl;when X is oxygen and Y is oxygen and c is zero, the group is1,3-benzodioxole-5-yl; and when X is nitrogen and Y is carbon and c iszero, the group is indoline-5-yl. In graphic formula IV, when X isoxygen and Y is carbon, the unsubstituted group is a chroman-6-yI; whenX is oxygen and Y is oxygen, the unsubstituted group is a1,4-benzodioxan-6-yl; and when X is nitrogen and Y is carbon, theunsubstituted group is 1,2,3,4-tetrahydroquinoline-6-yl. For brevity,these groups will be referred to herein as fused heterocyclicphenylgroups.

The preferred naphthopyran dye is 3,3-diphenyl-3-H-naphtho[2,1-b]pyranrepresented by the formula ##STR9## where R₁ to R₆ denote hydrogen.

The spiroxazines suitable in the present invention are known: see forinstance U.S. Pat. Nos. 3,562,172; 3,578,602; 4,215,010 and 4,342,668,all of which are incorporated by reference herein. Essentially, thespirooxazines suitable in the present invention may be described by theformula ##STR10## where: R₁. and R₂ independently represent a hydrogenor halogen (fluorine, chlorine or bromine) atom or a group chosen fromC₁ -C₅ linear or branched alkyl, C₁ -C₅ perfluoro-alkyl, C₁ -C₅ alkoxy,nitro or cyano;

R₃ and R₄ independently represent C₁ -C₅ linear or branched alkyl,phenyl or benzyl groups; or R₃ and R₄ when considered jointly with thecarbon atom to which they are linked form a C₅ -C₈ cycloalkyl group;

R₅ represents a C₁ -C₅ linear or branched alkyl, phenyl, benzyl or allylgroup;

R₆ represents a hydrogen atom or a C₁ -C₅ linear or branched alkyl groupor the group -NR₈ R₉ where R₈ is a C₁ -C₅ linear or branched alkyl,phenyl or benzyl group, R₉ is hydrogen or has the same meaning as R₈, orR₈ and R₉ when considered jointly with the nitrogen atom to which theyare linked form a cyclic structure comprising 5-12 members and possiblycontaining a further heteroatom chosen from oxygen and nitrogen; and

R₇ represents a hydrogen or halogen (fluorine, chlorine or bromine) atomor a group chosen from: C₁ -C₅ linear or branched alkyl, C₁ -C₅ alkoxy,cyano, thio-ether and carboxylated ester with 1-3 carbon atoms in theester portion, or represents an aromatic or heterocyclic condensed ring;X represents CH or N--.

In particular, the groups R₁ and R₂, when not hydrogen, can be linked inany of positions 4, 5, 6 and 7 of the indoline part of the molecule. Inaddition, the group R₇, if not representing hydrogen or an aromatic orheterocyclic condensed ring, can be present in any of the positions 7',8', 9'and 10' of the naphthalene part of the molecule.

In the preferred embodiment, photochromatic compounds corresponding togeneral formula (I) are used in which:

R₁ and R₂ independently represent a hydrogen atom or the methyl group;

R₃ and R₄ each represent the methyl group or jointly represent thecyclohexyl group;

R₅ represents the methyl group;

R₆ represents a hydrogen atom or the ---NR₈ R₉ group where the groups R₈and R₉ together with the nitrogen atom to which they are linked form apiperidyl, morpholyl, pyrrolidyl or hexamethyleneimino ring structure;and

R₇ represents a hydrogen atom; and

X represents CH.

Examples of preferred photochromatic compounds used according to thepresent invention are 1,3,3,4,5- or 1,3,3,5,6-pentamethyl spiro(indoline-2,3'-[3H]-naphtho-(2, 1-b)-(1,4)-oxazine); 1,3,3-trimethylspiro (indoline-2,3'-[3H]-naphtho-2, 1-b)-(1,4)-oxazine);1,3,3-trimethyl spiro(indoline-6-(1-piperidyl)-2,3'-[3H]-naphtho-2,1-b)-(1,4)-oxazine;1,3,3-trimethyl spiro(indoline-6'-(1-morpholyl)-2,3'-[3H]-naphtho-(2,1-b)-(1,4)-oxazine);1,3,3,4,5- or 1,3,3,5,6-pentamethyl spiro(indoline-6'-(1-piperidyl)-2,3'-[3H]-naphtho-(2,1 -b)-(1,4)-oxazine);and 1,3,3-trimethyl spiro (indoline-6'-(1-piperidyl)-9'-(methoxy)-2,3'-[3H]-naphtho-(2,1 -b)-(1,4)-oxazine).

The spiropyrans useful for the purposes of the present invention, arephotochromatic organic compounds which can be defined by the followinggeneral formulae (II), (III), (IV) and (V): ##STR11## in the precedinggeneral formulae: R₁₀ and R₁₁ represent alkyl or aryl groups;

R₁₂ represents an alkyl, aryl group or alkyl substituted group (such ashydroxyalkyl, halogenalkyl, carbalcoxyalkyl, alkoxyalkyl andaminoalkyl);

R₁₄ represents hydrogen or an alkyl, aryl or alkoxy; and

R₁₃ and R₁₅ represent hydrogen or mono- or poly-substitution groups,chosen among alkyl and substituted alkyl groups, or halogen, nitro oralkoxy.

Fulgides and fulgimides suitable in the context of the invention areknown and have been described in the literature (see, for instance,Applied Photochromic Polymer Systems, Edited by C.B. McArdle, BlackieUSA: Chapman & Hall, New York, 1992, pp. 80-120) incorporated byreference herein.

The inventive composition may be used in applications requiringphotochromic materials which were referred to above. Included arephotochromic lenses such as are described in U.S. Pat. No. 5,531,940,the specification of which is incorporated herein by reference.

The invention is further illustrated but is not intended to be limitedby the following examples in which all parts and percentages are byweight unless otherwise specified.

EXAMPLES

The following components were used to prepare the elastomers of thisinvention as illustrated in the examples:

Polyol A: A polytetramethylene glycol diol having an OH number of 112 mgKOH/g and a number average MW of ˜1000 g/mole.

Polyol B A polypropylene glycol diol having an OH number of 112 mg KOH/gand a number average MW of ˜1000 g/mole.

Polyol C A polyhexamethylene carbonate diol having an OH number of 56 mgKOH/g and a number average MW of ˜2000 g/mole.

Polyol D A polybutylene adipate diol having an OH number of 56 mg KOH/gand a number average MW of ˜2000 g/mole.

Polyol E A polypropylene glycol triol having an OH number of 550 mgKOH/g and a number average MW of ˜306 g/mole.

Polyol F A polypropylene glycol triol having an OH number of 370 mgKOH/g and a number average MW of ˜455 g/mole.

Catalyst Solution: A solution of 1 g of dibutyltin dilaurate and 99 g ofPolyol A.

Isocyanate A: The isocyanate was a mixture of isomers of4,4-dicyclohexylmethanediisocyanate having an isomer ratio of ˜20% byweight trans, trans, 50% by weight cis, trans, and 30% by weight cis,cis isomer.

Photochromic Dye A: 3,3-diphenyl-3-H-naphtho[2,1-b]pyran, availablecommercially as Variacrol Yellow L from Great Lakes Chemical Company

Photochromic Dye B:1,3-dihydro-1,3,3-trimethyl-spiro-2H-indole-2,3'-(3H)-naphtho(2,1-b)(1,4)oxazineavailable as Variacrol Blue A from the Great Lakes Chemical Company

Examples 1-10 illustrate the preparation of prepolymers that are used toprepare the photochromic materials of this invention.

Example 1

In a 3-necked flask equipped with an overhead stirrer, thermocouple, anda vacuum adapter, Isocyanate A (690.6 g; 5.26 eq.) was charged into thereactor and stirred at ambient temperature. Polyol A (809.4 g; 1.62 eq.)was preheated in an oven to 80° C. and added to the reactor. The mixturewas allowed to stir for ˜15 minutes, before adding Catalyst Solution A.(3.75 g). The reaction flask was evacuated (<0.1 mm HG) and held at 90°C. for 3.5 hours. An aliquot of the prepolymer was withdrawn andtitrated for isocyanate content using standard n-butyl amine titration.The isocyanate content was found to be 9.92% (theory; 10.2%).

Example 2

In a 3-necked flask equipped with an overhead stirrer, thermocouple, anda vacuum adapter, Isocyanate A (1062.0 g; 8.09 eq.) was charged into thereactor and stirred at ambient temperature. Polyol A (438.1 g; 0.876eq.) was preheated in an oven to 80° C. and added to the reactor. Themixture was allowed to stir for ˜15 minutes, before adding catalystsolution A (3.75 g). The reaction flask was evacuated (<0.1 mm HG) andheld at 90° C. for 3.0 hours. An aliquot of the prepolymer was withdrawnand titrated for isocyanate content using standard n-butyl aminetitration. The isocyanate content was found to be 19.80% (theory;20.2%).

Example 3

In a 3-necked flask equipped with an overhead stirrer, thermocouple, anda vacuum adapter, Isocyanate A (284.6 g; 2.17 eq.) was charged into thereactor and stirred at ambient temperature. Polyol B (333.5 g; 0.667eq.) was added to the reactor at ambient temperature. Catalyst A (1.55g) was added and the reaction mixture was heated (90° C.) under vacuum(<0.1 mm Hg) for 4 hours. An aliquot of the prepolymer was withdrawn andtitrated for isocyanate content using standard n-butyl amine titration.The isocyanate content was found to be 9.92% (theory; 10.2%).

Example 4

In a 3-necked flask equipped with an overhead stirrer, thermocouple, anda vacuum adapter, Isocyanate A (437.6 g; 3.34 eq.) was charged into thereactor and stirred at ambient temperature. Polyol B (180.5 g; 0.361eq.) was added to the reactor at ambient temperature. Catalyst A (1.55g) was added and the reaction mixture was heated (90 C) under vacuum(<0.1 mm Hg) for 4 hours. An aliquot of the prepolymer was withdrawn andtitrated for isocyanate content using standard n-butyl amine titration.The isocyanate content was found to be 19.90% (theory; 20.2%).

Example 5

In a 3-necked flask equipped with an overhead stirrer, thermocouple, anda vacuum adapter, Isocyanate A (246.6 g; 1.88 eq.) was charged into thereactor and stirred at ambient temperature. Polyol C (372.8 g; 0.373eq.) was added to the reactor at ca. 80cC. Catalyst A (1.55 g) was addedand the reaction mixture was heated (90° C.) under vacuum (<0.1 mm Hg)for 4 hours. An aliquot of the prepolymer was withdrawn and titrated forisocyanate content using standard n-butyl amine titration. Theisocyanate content was found to be 9.95% (theory; 10.2%).

Example 6

In a 3-necked flask equipped with an overhead stirrer, thermocouple, anda vacuum adapter, Isocyanate A (417.2 g; 3.18 eq.) was charged into thereactor and stirred at ambient temperature. Polyol C (201.8 g; 0.202eq.) was added to the reactor at ca 80° C. Catalyst A (1.55 g) was addedand the reaction mixture was heated (90° C.) under vacuum (<0.1 mm Hg)for 4 hours. An aliquot of the prepolymer was withdrawn and titrated forisocyanate content using standard n-butyl amine titration. Theisocyanate content was found to be 19.93% (theory; 20.2%).

Example 7

In a 3-necked flask equipped with an overhead stirrer, thermocouple, anda vacuum adapter, Isocyanate A (246.2 g; 1.88 eq.) was charged into thereactor and stirred at ambient temperature. Polyol D (372.8 g; 0.373eq.) was melted in an oven at ˜80° C. and added to the reactor. CatalystA (1.55 g) was added and the reaction mixture was heated (90° C.) undervacuum (<0.1 mm Hg) for 4 hours. An aliquot of the prepolymer waswithdrawn and titrated for isocyanate content using standard n-butylamine titration. The isocyanate content was found to be 9.90% (theory;10.2%).

Example 8

In a 3-necked flask equipped with an overhead stirrer, thermocouple, anda vacuum adapter, Isocyanate A (417.2 g; 3.18 eq.) was charged into thereactor and stirred at ambient temperature. Polyol D (201.8 g; 0.202eq.) was melted in an oven at ˜80° C. and added to the reactor. CatalystA (1.55 g) was added and the reaction mixture was heated (90° C.) undervacuum (<0.1 mm Hg) for 4 hours. An aliquot of the prepolymer waswithdrawn and titrated for isocyanate content using standard n-butylamine titration. The isocyanate content was found to be 19.90% (theory;20.2%).

Example 9

In a 3-necked flask equipped with an overhead stirrer, thermocouple, anda vacuum adapter, Isocyanate A (559.0 g: 4.26 eq.) was charged into thereactor and stirred at ambient temperature. Polyol A (338.7 g; 0.677eq.) was preheated in an oven to 80° C. and added to the reactor. Themixture was allowed to stir for ˜15 minutes, before adding catalystsolution A. (2.25 g). The reaction flask was evacuated (<0.1 mm HG) andheld at 90° C. for 3.0 hours. An aliquot of the prepolymer was withdrawnand titrated for isocyanate content using standard n-butyl aminetitration. The isocyanate content was found to be 16.40% (theory;16.7%).

Example 10 (comparative example):

Isocyanate A (554.9 g; 4.23 eq.), Polyol E (45.1 g; 0.442 eq.) andcatalyst solution A (1.5 g) were combined at room temperature in a3-necked flask equipped with an overhead stirrer, thermocouple, and avacuum adapter. The mixture was allowed to stir under vacuum (<0.1 mmHG) as the temperature was increased over ˜30 minutes to 100° C. After 4hours at 100° C., an aliquot was removed and titrated for isocyanatecontent (found 26.3% NCO; theory; 26.5%).

Examples 11-36

General Procedure for Preparing the Photochromic Polyurethanes

The prepolymers from Examples 1-10 were cast to form photochromicpolyurethanes according to the following general procedure. Theprepolymer was heated in vacuo (<0.1 mm HG) with stirring to 80° C. andthe photochromic dye was added at a level sufficient to give 0.1 wt. %in the cast polyurethane material. The amount of prepolymer indicated inTable 1 was weighed into a disposable glass container. The desired chainextender was warmed in an oven to 60° C. before combining with theprepolymer. The mixture was stirred for 30 seconds and subsequentlypoured into an aluminum tray (˜3"×6"×1") that had been pre-treated witha silicone based mold release (MR 515) available from ChemTrend Inc. Thetray containing the casting was cured in an oven (110° C.) for 18 hours.The plaque was removed from the tray and analyzed for photochromicbehavior as described below.

                  TABLE 1                                                         ______________________________________                                                       Prepolymer                                                                              Chain    Chain  Photo-                                    Prepolymer                                                                              Amount    Extender Extender                                                                             chromic                              Ex.  (Ex. #)   (g:meq)   Type     (g:meq)                                                                              Dye                                  ______________________________________                                        Description of Elastomers Example 11 through 22                               11   1         90.8:214  1,4-butanediol                                                                         9.17:204                                                                             B                                    12   1         90.8:214  1,4-butanediol                                                                         9.17:204                                                                             A                                    13   2         83.2:392  1,4-butanediol                                                                         16.8:373                                                                             B                                    14   2         83.2:392  1,4-butanediol                                                                         16.8:373                                                                             A                                    15   1         81.3:192  Polyol E 19.8:194                                                                             B                                    16   1         81.3:192  Polyol E 19.8:194                                                                             A                                    17   2         68.7:324  Polyol E 31.4:308                                                                             B                                    18   2         68.7:324  Polyol E 31.4:308                                                                             B                                    19   3         90.9:215  1,4-butanediol                                                                          9.1:202                                                                             B                                    20   3         81.3:192  Polyol E 18.7:183                                                                             B                                    21   4         83.1:394  1,4-butanediol                                                                         16.9:376                                                                             B                                    22   4         68.5:324  Polyol E 31.5:309                                                                             B                                    Description of Elastomers Example 23 through 36                               23   5         90.8:215  1,4-butanediol                                                                          9.2:204                                                                             B                                    24   5         81.3:193  Polyol E 18.7:183                                                                             B                                    25   6         83.1:394  1,4-butanediol                                                                         16.9:376                                                                             B                                    26   6         68.5:325  Polyol E 31.6:310                                                                             B                                    27   7         90.8:214  1,4-butanediol                                                                          9.2:204                                                                             B                                    28   7         81.4:192  Polyol E 18.6:182                                                                             B                                    29   8         83.1:394  1,4-butanediol                                                                         16.9:375                                                                             B                                    30   8         68.5:324  Polyol E 31.5:309                                                                             B                                    31   9         79.1:309  1,4-butanediol                                                                         13.2:294                                                                             B                                    32   9         83.6:326  1,4-butanediol                                                                         14.0:311                                                                             A                                    33   9         57.8:226  Polyol E 22.2:218                                                                             A                                    34   9         57.8:226  Polyol E 22.2:218                                                                             B                                    35   10        89.6:561  Polyol F 80.2:529                                                                             A                                    36   10        89.6:561  Polyol F 80.2:529                                                                             B                                    ______________________________________                                    

Determining Photochromic Behavior of the Polyurethanes

The initial absorbance value (A₀) for each plaque was recorded at theλ_(max) of the photochromic dye (λ_(max) of Dye A=425 nm; λ_(max) of DyeB=610 nm). Absorbance is defined as the natural logarithm of the inverseof the ratio of transmitted over incident light intensity and isobtained from transmission spectroscopy. The plaque was then exposed toa hand-held light source (Spectroline Model EN--280 L; 365 nm output).After 1, 2, 4 and 10 minutes of exposure to the light, the opticalabsorption of the plaque (A) at the λ_(max) of the photochromic dye wasre-recorded. These values were used to calculate a .sub.Δ A value aftereach exposure, where .sub.Δ A is defined as A-A₀. The value of the.sub.Δ A after 2 minutes was divided by the .sub.Δ A after 10 minutesand multiplied by 100 to give a parameter that indicates the percentageof darkening that occurs within two minutes in the particular matrix.This value (.sub.Δ A @ 2 minutes) for each of the polyurethanes is givenin Table 2.

After 10 minutes of exposure to the light source, the sample was placedin the spectrometer and the absorption of the plaque at the λ_(max) ofthe dye was monitored. The time at which the .sub.Δ A value decreased to50% of its initial value (immediately after the 10 minute illumination)was recorded and is given in Table 2 as the T₅₀ for fading of the dye inthe particular matrix.

The photochromic performance (darkening and fading behavior) issummarized in Table 2 below. Examples 11-34 show acceptable performance,defined as a .sub.Δ A @ 2 minutes of greater than 50% and a T₅₀ of<2minutes. The comparative Examples 35 and 36, where the polyurethaneswere prepared without the requisite high MW component do not haveacceptable photochromic performance by this definition.

                  TABLE 2                                                         ______________________________________                                        Photochromic Behavior of Elastomers from Examples 11-36                                     .increment.A @ 2 minutes                                                                  T.sub.50 Fade                                       Example       (% of max)  (sec.)                                              ______________________________________                                        11            100          8                                                  12            94          15                                                  13            92          30                                                  14            88          60                                                  15            87          92                                                  16            79          15                                                  17            85          93                                                  18            89          74                                                  19            86           3                                                  20            72          11                                                  21            83          52                                                  22            87          73                                                  23            94          15                                                  24            100         15                                                  25            89          99                                                  26            79          80                                                  27            90          13                                                  28            77          12                                                  29            93          110                                                 30            88          50                                                  31            96          30                                                  32            95          25                                                  33            97          35                                                  34            95          35                                                  35            100         150                                                 36            83          155                                                 ______________________________________                                    

Although the invention has been described in detail in the foregoing forthe purpose of illustration, it is to be understood that such detail issolily for that purpose and that variations can be made therein by thoseskilled in the art without departing from the spirit and scope of theinvention except as it may be limited by the claims.

What is claimed is:
 1. A photochromic polyurethane characterized by a.sub.Δ A at 2 minutes of greater than 50% and a T₅₀ of less than 2minutes consisting essentially of:a) an isocyanate reactive mixtureconsisting essentially of:i) from about 40 to about 85% by weight of oneor more polyols having a nominal functionality of from 2 to 4 and amolecular weight of from 500 to 6000 g/mol; ii) from about 15 to about60% by weight of one or more diols or triols or mixtures thereof havinga functionality of from 2 to 3 and molecular weights of from 62 to 499;b) an aliphatic polyisocyanate having a functionality ranging from about2 to about 3; and c) a photochromic compound selected from the groupconsisting of spirooxazines, fulgides, fulgimides, and naphthopyrans,wherein the photochromic compound c) is present in an amount of from0.01 to 5 parts per hundred parts by weight of the isocyanate reactivemixture a).
 2. A photochromic polyurethane according to claim 1, whereinsaid one or more polyols has a molecular weight of from 1,000 to 3,000g/mole.
 3. A photochromic polyurethane according to claim 1, whereinsaid one or more polyols has a functionality of about
 2. 4. Aphotochromic polyurethane according to claim 1, wherein said one or morepolyols is selected from a group consisting of polyether polyols,polyester polyols and polycarbonate polyols.
 5. A photochromicpolyurethane according to claim 4, wherein said polyether polyol isselected from a group consisting of polypropylene glycol andpoly(tetramethylene glycol).
 6. A photochromic polyurethane according toclaim 4, wherein said polyester polyol is butylene adipate.
 7. Aphotochromic polyurethane according to claim 4, wherein saidpolycarbonate polyol is polyhexamethylene carbonate.
 8. A photochromicpolyurethane according to claim 1, wherein said diol is 1,4-butanediol.9. A photochromic polyurethane according to claim 1, wherein componenta) ii) is a polypropylene oxide triol.
 10. A photochromic polyurethaneaccording to claim 1, wherein said aliphatic polyisocyanate has afunctionality of about
 2. 11. A photochromic polyurethane according toclaim 10, wherein said aliphatic polyisocyanate comprises mixtures ofthe stereoisomers of bis-(4-isocyanatocyclohexl)-methane.
 12. Aphotochromic polyurethane according to claim 1, wherein saidphotochromic compound is 3,3-diphenyl-3-H-naphtho [2,1-b]pyran.
 13. Aphotochromic polyurethane according to claim 1, wherein saidphotochromic compound is1,3-dihydro-1,3,3-trimethyl-spiro-2H-indole-2,3'-(3H)-naphtho(2,1-b)(1,4)oxazine.